KeyStore.store can write wrong type of file

Create a PKCS12 keystore. Initialize as empty then attempt to load from a empty file. The load fails as expected. If you then write the keystore with KeyStore.store(OutputStream, char[]) you end up with a JKS keystore. The reverse also happens - if you start with a JKS keystore you end up with PKCS12 after the store.

Here's a small test:

public class ksload {

  public static void main(String ... args) throws Exception {
    
    File file = new File(args[0]);
    char [] pw = {'x'};
    KeyStore ks = KeyStore.getInstance("PKCS12");
    
    ks.load(null, null);
    
    try (InputStream in = new FileInputStream(file)) {
      ks.load(in, pw);
    } catch (Exception e) {
      System.out.println(e);
    }
    
    try (OutputStream out = new FileOutputStream(file)) {
      ks.store(out, pw);
    } catch (Exception e) {
      System.out.println(e);
    }
  }
}

Run it with an argument naming an empty file.

Seems OK in Java 1.8.